The record of Early Tertiary North Atlantic volcanism in sediments of the North Sea Basin

Volcaniclastic deposits in sedimentary sequences of the North Sea Basin and adjacent areas indicate that two phases of early Palaeogene explosive volcanism took place in the north-eastern Atlantic region. The earlier, late Palaeocene (NP5-NP6) phase involved significant activity along a N-S trend that included both the British and Faeroe-Greenland Tertiary volcanic provinces. The later phase spanned the latest Palaeocene and early Eocene (NP9 to NP13), with much or all of the activity taking place in the Faeroe-Greenland Province. Early ashfalls of mixed basaltic to silicic compositions may have included contributions from the final phase of British volcanism, but were followed by a series of 200 or more tholeiitic ashfalls of Faeroe-Greenland provenance. These tholeiitic eruptions appear to have marked the onset of separation of Greenland from Europe in mid NP10 times. A subsequent return to pyroclastic activity of more variable compositions appears to have marked the re-establishment of stresses within the E Greenland crust that continued throughout the early Eocene (mid NP10 to end NP13). The mechanism of eruption of the tholeiitic ashes, which are equivalent to a magma volume of several thousand cubic kilometres, is uncertain, but they would appear to involve hydrovolcanic processes.